Circuit breaker



Aug'v `15, 1944 G. G. GRlsslNGER ET A1. 2,356,050

CIRCUIT BREAKER Filed Oct. 18, 1941 3 Sheets-Sheet l WITNESSES:

G. G. GRISSINGER ETAL C IRCUIT BREAKER Filed Oct. 18, 1941 3 Sheets--Sheefl 2 I/ l 37 5. L --u I fr @a 12; .fm '11/ fr M k@ gj 3 51 as s l im 107 1Q 39 7 115' 37 0.? fli'glf 7 117 59 /f 28 l 21j@ l\ 91 11s i 157 145 9 73 5I 152 1351 g5 Z291 I l 1 135 187 83 l"``\ [77181 L im:

I* Irl 203 01 169'@ I 207 191 L3 le? 165 205 193 167 9 161 J9 197 WITNESSES:

George 671235272967' and Tyre Lindstrom.

BY 1/ df/ ATTORNEY conditions, said spring being also operable? Patented Aug. 15, 1944 l UNITED sTATEs PATENT oEEicE CIRCU'ITBREAKER George (nGrissinger,l Wilkinsburg, and Ture LindstromVEdgewood, Pa., assignors to West inghouse Electric Jr'Manufacturng Company, Eas1lpittsburgh,ula. ,a corporation of Pennsyli van n v f an'platoonl oetoberis, "194i, sensi No. 415,617

` "'1tft/*ciienne.V tenzone-ssi This invention relates to circuit breakers and Ymember in responseto predetermined abnormal more particularly to circuit breaker c'f't'hejtype Aconditionsin the circuit. used for controlling light to an -md ate werr -"=Anot`her object of the invention is the provision distribution circuits. y K lof; the circuit breaker as previously described in An object of the invention ist I `whichjtlnt opening movement of the breaker acts improved circuit breaker whichi v n hrough theresilient means to reset the tripping sponse to overload currents and"iri responseto 'm'embnundervoltage conditions in the circuiti-.controlled n jAntherlobiject of the invention is the provision by the breaker to automatically interruptthe cir-L '.ofla circuit breaker as previously described in cuit. l, mfwhich fthe resilient means forI tripping the break- Another object; of the invention is the povis jerQanclior` resetting the trip member permits oversion of a circuit breaker in which a spring'm'ean's travel in 'both directions 0f the Darts t0 .Which controlled by a trip device is operativ'e'uponY the Y theleSilieDt means iS Connected.

occurrence of predetermined abnormal: conci-fy f `Another object 0f the invention is the provision tions to cause an automatic opening perationof lorrcffagfcircuit vbreaker in which the movement of the breaker and which is also operable tol reset 'tlieeperating mechanism to open the circuit rethe trip device upon opening of the breaker. i .sets'fthe trip device.

Another object of the invention is to provide "Thencvel 'features that are considered chara circuit breaker with an improved undervolta'ge eteiistie `ofthe invention are Set forth in Daftrip device in which a spring acts to cause an au 'C20 itileilll in the lappended Claims. The invention tomatic opening operation of the breaker in're itself, however, both as to structure and Operasponse to predetermined abnormal undervoltag tiOiLtOgethei With additional Objects and advantagesfthereof, will be best understood from the restore the trip device to reset, position .upon vfollowing description of one embodiment thereof opening the contacts. fl "25 when read in conjunction with the accompanying Another object of the invention is the 'provision y. dl'WingS, in Whiehr of a circuit breaker havingan improved tripdef y Figure 1 is a side elevational view of a threevice operable in response to predetermined"*un-l.vv v- ,'DOlc circuit breakerembodying the Principles 0f dervoltage conditions to cause an opening cipiervfv thelinvellten;

tion of the contacts and in which thetrip device 930i" 'YFiErZ is a vertical Sectional View through the is automatically reset upon openingifof tlie-"con-iv center pole of the breaker;

' Fig. 3' is an enlarged fragmentary horizontal tacts. 4

Another object or the invention is' the'provision y sectional view of a part of the trip mechanism; of a circuit breaker having y9, switch"member Fig. 4 is `an enlarged detail View `0f the Underrnovable to open and close the circuit wim-:a .a5 ,Voltage trip deveegshown in tripping position;

i spring operated trip device in which"`-`the`swltch Fig. 5 is. an enlarged vertical sectional view tripping energy in the spring upon mem-ber acts through the spring toreset the trip taken on line V-V of Fig. l; and i device upon opening of the bre'ak nd to store Fig. 6 is an enlarged sectional view taken on ment of the switch member. y

y y o dervoltage trip device. Ano-ther object of the invention -isthe provision Referring to Fig. 2 of the drawings, the breaker ingmove.. the center line of the resilient linkage of the un-` of a circuit breakerhaving a novel trip device iS Provided With all Operating mechanism 60mcomprising a spring meansvin which energy is' mon to all of the poles which is mounted in a U- stored by the closing movement of'the breaker shaped main frame i5 Comprising a Pair 0f frame and which is released to cause automatic opera- 45 members i1 rigidly Connected by a CTOSS memtion of the breaker mechanism in response to preber |19. The frame I6 is mounted on the central determined undervoltage' conditions in the cirportion of a base Il of insulating'material and iS cuit. secured thereto by means of bolts 2| and 23. The Another object of the invention is the provision Outer ends of the frame members i7 are rigidly of a circuit breaker having a novel trip device in 50y COImeCted by a CI'OSS member 25. which a resilient means is connected between a The bolt 23 extends through the cross member tripping member and a part movable with the I9 and serves to rigidly secure a connector 21 movable contact assembly, the tripping member of conducting material to the cross member and being normally held against trippingmovement to the base Il. A shaft 29 extending through by an` electromagnet which releases the tripping 55 an opening in the connector 21- and through openings in the frame members I 1 pivotally supports a pair of arms 3| having their free ends integral with a Contact arm 30 for the center pole. The contact arms 30 (Fig. 1) for the outer poles are identical with the arm 30 for the center pole but are not provided with arms 3|. The contact arms 30 for the outer poles are rigidly secured to a tie bar 61 which extends across all of the poles and which is clamped to the center pole contact arm 30 by means of a split clamp 10 and a screw 1|. Rectangular tubes 69 of insulating material between the tie bar 51 and contact arms 30 for the several poles serve to insulate the three movable contact arms and their associated contacts from the tie bar 61.

The movable contact structures and the stationary contacts for the several poles are alike for which reason only the contacts for the center pole will be described. The Contact arm 30 for the center pole pivotally carries a main movable contact member 41 and a movable arcing contact member 55. The main contact member 41 is pivoted on a pivot pin 49 supported in projections 5| of the contact arm 30, and the movable arcing contact member 55 is pivoted on a pivot pin 51 supported in projections 59 of the arm 30. The main movable contact member 41 carries a contact 33, and a contact 35 is secured to the arcing contact member 55. These contacts 33 and 35 are adapted to engage respectively xed contacts 39 and 31 secured on a conductor 4| which is in turn secured to the base by means of bolts 43. The conductor 4| extends upwardly and is bent at right angles, the bent portion extending through an opening in the base l l to form a terminal connector 45.

A spring 53 compressed between a spring seat on the contact arm 30 and a spring seat on the main contact member 41 provides contact pressure for the main contacts 33-39 when the contact arm is in the closed position. Contact pressure for the arcing contacts 35-31 is provided by a spring 63 surrounding a rod 6| pivotally connected to the arcing contact member 55 and slidable through an opening in a spring seat on the contact arm 30. The spring 63 is compressed between a washer 65 seated on a shoulder on the rod 6| and the spring seat on the contact arm 30. The rod 6| has a nut 15 on the outer end thereof which acts to limit counterclockwise rotation of the arcing contact member 55 about its pivot when the contact arm 30 is moved to open the contacts. Counterclockwise movement or the main contact member 41 is limited by a projection 13 thereon striking the body of the contact arm 30. The adjustment of the nut 15 on the rod 6| is such that the arcing contacts 35 31 open shortly after the main contacts 33 39 open.

When the contact arm 30 is operated to open the contacts, the arc across the arcing contacts '3S-31 resulting from the rupture of the current is drawn into an are extinguisher indicated generally at 15 where it is cooled and extinguished. Any suitable arc extinguisher may be employed the one illustrated comprising, generally. a stack of slotted plates disposed adjacent the paths of travel of each of the arcing contacts 35. The plates serve to draw the arc towards the ends of the slots where it is broken up into a plurality of short arcs which are quickly cooled and extinguished.

The movable arcing Contact member 55 is connected by a exible shunt 'conductor 11 to the main contact member 41 and another exible shunt conductor 19 connects the main contact member 41 to the connector 21. The connector 21 for the center pole is secured to the cross member |9 of the frame Ii by the bolts 23, and the connectors 21 for the outer poles are bolted to the base with a spacer (not shown) between the base and each of the connectors in order to align the members 21 of the outer poles with the corresponding members 21 for the center pole. A conductor 8|, secured to the connector 21 by means of bolts 14 extends downwardly therefrom and is bent at right angles. The horizontally disposed portion of the con- `ciuctork extends between the legs of a U-shaped tripping magnet core |8| and projects through an opening in the base where it forms a terminal connector 83 which, together with the ter mina] connector 45, serves to connect the breaker in an electrical circuit.

The electrical circuits for the several poles of the breaker are essentially the same, therefore, only the circuit for the center pole will be traced. This circuit extends from the terminal connector 45 through the conductor 4|, the main contacts 33-39, the main contact member 41, the flexible shunt conductor 19, the connector 21, the conductor 8| to the terminal connector 83. The circuit for the arcing contacts 31-35 extendsfrom the terminal connector 45, through the conductor 4|, the arcing contacts (l1-35, the flexible shunt conductor 11, the main contact members 41 and through the previously described circuit to the terminal connector 83.

The contact arm 30 for the center pole is biased in a clockwise or opening direction by means of a pair of springs 85 (only one being shown). springs are tensioned between the contact arm 30 and a x'ed pivot 81 supported in the main frame I6. In the closed position of the breaker, the center pole contact arm 30 and consequently all of the contact arms are releasably restrained in closed contact position (Fig. 2) by means of a toggle and linkage mechanism which is collapsible to cause opening of the contacts. 'I'he toggle and linkage forms a part of the common operating mechanism.

This collapsible linkage includes a lever 89 pivotally mounted on a fixed pivot 9| supported on the main frame |8. The lever 89 comprises a pair by a main operating toggle comprising toggle The toggle link 93 has one end pivoted on a pin |0| supported on the lever 89 and the link 95 is pivoted on a pivot pin 99 on the arm 3|. The links 93 and 95 are pivotally connected by a knee pivot pin 91. The toggle link 95 comprises a pair of links rigidly connected by means of an integral cross bar |5.

The free end of the lever B9 is connected by means of a link |03 to one arm of a lever |05 pivoted on the fixed pivot 81. The other arm of the lever |05 is pivotally connected to a toggle link |01 of a tripping toggle comprising the link |01 and a toggle link |09. The link |49 is pivoted on a xed pivot ||3 supported on the frame I6 and comprises a pair of links joined near the pivot |3 by a yoke |23 provided with projections |25 and |21. The toggle link |01 comprises a pair of links connected by a yoke bent portion to which is secured an extension |2| of insulating material. The toggle links |01 and |09 are pivotally connected by a knee pivot pin The purpose of the extension |2| is to co- I9 having a` operate with a part connected to a manually operable handle I4| to manually trip the breaker in` a manner to be more fully described later. The lever |05 and the link |03 each comprise a pair of members rigidly connected by yokes substantially as illustrated. y

The linkage just described serves to releasably hold the contact assemblage including the movable contacts for allsof the poles of the breaker in closed contact position. In the closed position, the main operating toggle 93-95 is overcenter above a line through the center of the pins 99-|0|, and a second toggle, one link of which comprises the overcenter links 93-95 and the other link of which comprises the lever 89, is overcenter above a line through the center of the pins 99 and 9 I. The overcenter movement of the main operating toggle 93-95 is limited by the projecting end of the link 93 engaging the cross bar ||5 of the link 95.

With the main operating toggle 93--95 and the toggle comprising the links 93--95 and the lever 89 in the overcenter position, as shown in Figure 2, the springs 85 bias the lever 99 in a clockwise direction. Movement of the lever 89, however,

is normally prevented by the tripping toggle |01-|09 which is overcenter to the left of a line through the center of the fixed pivot I I3 and the point of connection of the toggle link |01 with the lever |05. The toggle |01|09 is biased to its overcenter position by a spring |28 ten-` sioned between the yoke ||9 andthe fixed pivot I |3. The overcenter position of the tripping toggle I01|09 is adjustably determined by the projection |25 of the yoke |23 engaging an adjusting screw |29 in the cross member 25 of the frame. The tripping toggle |01|09 in its overcenter position, acting through the lever |05 and the link |03, prevents clockwise movementv of the lever 89 and consequently holds the movable contact assemblage in the closed contact position against the biasing influence of the springs 85.

The tripping toggle |01|09 is adapted to be moved overcenter outwardly in a direction to cause its collapse to eiect opening of the contacts by means of an overload trip device indicated generally at |33 (Figs. l, 2 and 4). The overload trip device is operable in response to overload currents in the circuits of the breaker to actuate a trip rod |35 and cause collapse oi' the tripping toggle |01-|09. The trip rod |35 is slidable vertically through a shunt trip coil (not shown) enclosed in a casing |38 attached to the main frame I6. The shunt coil is adapted to be energized from a suitable source and in a manner well known in the art, to operate thetrip rod and trip the breaker from a remote point.

When operated either by the shunt coil or by the trip device |33, the trip rod |35 is thrust upwardly and strikes the projection |21 of the yoke |23 and rocks the toggle link |09 clockwise about the fixed pivot II3. This movement of the link |09 causes collapse of the tripping toggle |01|09 permitting clockwise movement of the lever 89 which permits the springs A85 to rock the movable contact assemblage clockwise to open the contacts.

The main operating toggle 93--95 does not immediately collapse but the force of the springs 85 applied through the contact arm 303| and the main operating toggle causes collapse of the toggle comprising the links 93-95 and the lever 99 which results in clockwise movement of the lever 89, This movement is transmitted throughv the link |03 and the lever |05 to complete the collapse of the tripping toggle I01-|09.

j time the knee pin 91 of the toggle has passed overcenter below the line 99-IOI the weight of the parts act to complete the collapse of the toggle 93-95 and causes the linkage 89, |03,r |05 and the tripping toggle |01-I09 to be automatically reset to their normal position. The main operating toggle 93-95 remains in collapsed condition until the contacts are reclosed.

'The contacts are, closed manually by operation of the previously mentioned handle |4|. The handle is rotatably mounted in a bracket |43 of insulating material secured to the outer end of the main frame I6. Operatively connected to the vmechanism (not shown) operated by the handle isalink |5|. The lower end of the link |5| is recessed and straddles a pulley-shaped roller |53 rotatably mounted on a. cross member |41 rigidly connecting the outer ends of aipair of spaced contact closing levers |45. These levers are disposed on the outside of the frame |6 and are pivotally supported on the ends of the fixed pivot 9| which project beyond theframe members |1. The inner ends of the lever |45 are rigidly connected by across member |49. Spaced projections |52 extending from the center portion o! vthe cross"member |49 support a pivot*l pin I5 upon which is rotatably mounted a roller |55.

The contacts are closed manually by clockwise rotation ofthe handle |4I. This movement of the handle, through connections (not shown) thrusts the link |5| downwardly and due to its engagement with the roller |53, rotates the closing lever |45 in a clockwise direction. Dun'ng this movement of the lever |45, the roller |.55 engages the link 93 of the now collapsed main operating toggle 93-95 and moves this toggle to its overcenter position. Since at this time the tripping toggle |01|09 has beenrestored to its overcenter position, rotation of the lever 89 is prevented and consequently the force applied by the roller |55 to straighten the toggle 93 -95 rotates the contact arm 30 counterclockwise to close the contacts and to tension the springs 85. The clockwise movement ofthe closing lever |45 moves the toggle 93-95 overcenter above the line 99'-|0I so that the contacts are held in the closed position until the breaker is again tripped.

Upon release of the handle |4| following a contact closing operation, a spring |59 tensioned between the closing lever |45 and the frame` I6.

restores the lever |45 in a counte'rclockwise direc tion. This movement of the lever |45 and the roller |53 thrusts the link |5I upwardly to re-J store the handle |4| to its neutral position.

The closing lever |45 may be operated to automatically close the contacts through the agency of a motor |39 (Fig. 2) mounted on a plate attached to the side of the frame I0. The motor |39 may be energized from any suitable source. When energized, the motor is adapted, through a suitable driving connection, to rotate a crank disc |30. This disc carries an anti-friction roller |3| which engages a cam face |32 on an arm |34 secured to one side of the closing lever and rotates the arm and the closing lever |45 clockwise to effect4 closing of the contacts in the previously passes out of engagement with the arm |34, the spring' |59 acts to restore the lever |45 to its normal position. The motor |39 is deenergized by a suitable limit switch (not shown).

The circuit breaker may be tripped manually by rotation of the handle |4| through a. small angle in a counterclockwise direction from its neutral position. When the handle is rotated in tripping direction, a projection (not shown) on the link |5| engages the extension |2| on the yoke ||9 of the toggle link |01 and rocks the link counterclockwise about its point of'connection with the lever |05. This moves the tripping toggle |01--I09 overcenter in a direction to cause its collapse and effects opening of the contacts in the previously described manner.

As previously stated, the trip rod |35 is operated to effect tripping of the breaker by means of a current responsive trip device |33. There is a trip device |33 provided for at least two of the poles of the breaker but since the trip devices are alike only the one for the center pole will be described.

The trip device includes the U-shaped magnet core |6| and a frame comprising substantially parallel side members |63 rigidly connected at their outer ends by a yoke |65. The members |63 are provided with mounting feet |61, and bolts |69 extend through openings in the feet |61 and in the magnet core |6| and in the base to rigidly secure the core and frame to the base. A trip lever |13 is pivotally supported on a pivot |15 mounted in the frame |63. The trip lever |13 comprises a pair of spaced levers having an armature |19 secured to one end and being rigidly connected by a yoke |11 at the other end. The v trip lever 13 is biased against operation by the magnet |6| by means of a pair of springs |9| (Figs. 2, 3 and 4) having one end secured to the yoke |11 and the other end attached to a vertically movable plate l93. The plate |93 cooperates with an adjusting screw |95 which is provided with a knurled head |91 bearing against the bottom side of a formed projection |99 of the yoke |65. Rotation of the screw |95 moves the plate |93 and thereby adjusts the tension of the spring |9| to vary the tripping load of the breaker. A scale plate 203, supported on spaced projections 20| of the yoke |65, bears indicia indicating the adjustment of the spring |9| or the tripping point of the breaker. An adjustable stop screw 205 provided with a lock nut 201 determines the open air gap of the magnet.

A trip bar |81 is rotatably supported in a bracket |89 secured to the casing |36 for the shunt coil. The trip bar extends across all of the poles of the breaker and is provided with an arm |85 for each pole, the center one of the arms being in alignment with the lower end of the trip rOd |35. An adjusting screw |8| is mounted in each of the yokes |11 in alignment with the corresponding arm |35.

Normal rated current flowing through the circuit of the breaker, including the conductor 0|, causes slight energization of the magnet |6| but not sufficient to overcome the tension of the springs 9|. Upon the occurrence of an overload current above a predetermined value in the circuit of anypole. the ow of current through the conductor 8| causes energization of the magnet sumcient to overcome the spring |9| and attract the armature |19 rocking the trip lever |13 counterclockwise. At this movement of the trip lever |13, the screw |6| rotates the arm |65 and the trip bar |81 in a clockwise direction and thrusts the trip rod |35 upwardly to trip the breaker in the previously described manner.

The construction of the circuit breaker as thus far described with the exception of the trip device |33 is essentially the same as that fully disclosed in the copending application of John W. May and Ture Lindstrom Serial No. 391,625, led May 3, 1941, assigned to the assignee of this invention.

In addition to tripping the breaker in response to overload currents, it is desired also to trip the breaker when the voltage in the circuit controlled by the breaker drops below a predetermined value. For this purpose, an undervoltage trip device and an undervoltage trip mechanism are provided.

The undervoltage trip device includes an electromagnet 209 (Figs. l, 3 and 4) comprising a U-shaped core 2|I mounted between the legs of a U-shaped frame 2|3 secured to the base by screws 2|5, and an armature 2|9. Each of the two legs of the magnet core 2|| is surrounded by a coil 2|1 which are connected in series relation and connected across the circuit of the breaker. The armature 2|9 is mounted between a pair ot spaced arms 22| pivotally supported on a pivot pin 223 mounted on the U-shaped frame 2|3. The undervoltage trip mechanism includes a trip member or lever 225 comprising a pair of levers pivotally supported on a pivot 221 which is mounted on the U-shaped frame 2|3. The levers 225 are rigidly connected at their outer ends by a yoke 229. `'I'he trip lever 225 is operatively connected to the armature 2 9 of the trip-magnet by means of a pair of links 23| (see also Fig. 5). Each link 23| is pivoted on a stud 233 projecting outwardly from the corresponding lever 225. The links are bent inwardly (Fig. 5) and are pivotally connected by means of a pin 234 to the stem 235 of a T-shaped member having its cross member 231 secured to the arms 22| of the armature.

The yoke 229 extends toward the right (Fig. 4) and has an adjusting screw 239 secured therein by means of a lock nut 24|. The screw 239 is in alignment with an arm 243 similar to the arms |85 secured to the trip bar |81 so that upon counterclockwise movement of the undervoltage trip lever 225, the screw rocks the trip bar clockwise to trip the breaker as previously described.

The trip lever 225 is connected by a resilient linkage 245 to an arm241 supported on a pivot 249 which is supported in a U-shaped bracket 25| secured to the underside of a horizontally disposed bar 253. This bar has a vertically extending end 255 which is secured to a large U- shaped bracket 251 mounted on the base by means of screws 259.

The resilient linkage 245 forms a part oi the trip mechanism and includes a cylinder 26| (Figs, 1, 3, 4 and 6) pivotally connected to the trip lever 225 by a pin 263 extending transversely through openings in the levers 225 and openings in the walls of the cylinder. A cylindrical sleeve 265 (Fig. 6) fitting in the end of the cylinder 26| whic his connected to the trip lever 225` is held in place by the pin 263 extending transversely through openings therein. A shouldered rod 261 pivotally connected to the arm 241 by a pin 269 projects into the cylinder 26| and has a screw 21| (Fig. 6) in the end thereof. The head of the screw 21| is slidable in thc sleeve 65. A spring 213 is compressed between a washer 215 seated against the inner end of the sleeve 265, and a washer 211 seated against an inner shoulder of The construction is such that the cylinder 26 I.

the head ofthe screw 21| engages the washer 215 and the shoulder on the rod 261 engages the washer 211, so that the compression of the spring 213 will be increased when the rod 261 and the cylinder 26| are moved relatively to each other in either direction.

The arm 241 is rigidly connected by a yoke 219 to a short arm 23|, pivoted on the pivot 249 and secured to a vertically extending arm 283 also pivf otally supported on the pivot 249 adjacent one end of the bracket 25|. A yoke 285 (Fig. 3) connects the arm 283 to an arm 281 pivotally supported on the pivot 249 adjacent the other end of the bracket 25|. The free end of the arm 283 (Fig. 1) is operatively connected to a projection 289 on the contact arm 3l) for the left-hand pole of the breaker, as viewed from the front of the breaker, by means of a link 29 I.

The bar 253 and the U-shaped bracket 251 constitute a support means for an auxiliary switch device the operation and purpose of which are well known in the art and which forms no part of the present invention.

A time delay device comprising an oil dash pot provides a time delay during which the voltage of the circuit may return to normal without having tripped the breaker. The time delay device includes a plate 292 (Fig. 5) to which a dash pot 293 is attached by means of a screw thread. The plate 292 is mounted on angular portions of the U-shaped frame 2|3 by screws 294. A piston 295 engages a headed screw 291 in the lower end of a piston rod 299 having its upper end pivotally connected to the armature 2| 9 by means of the pin 234 and ystern 235. The upper end of the rod 299 is bifurcated to straddle the stem 235 to provide a pull along the center line of the armature. A compression spring 30| is provided to restore the piston 295 to its lower position after an operation of the undervoltage trip device.

The parts of the undervoltage trip device are shown in Figure 1 in their lnormal position, that is, in the positions they assume when normal rated voltage is applied across the circuit controlled by the breaker. In this condition, the link age 245 is lntension, that is the rod 281 is drawn out of the cylinder 26| giving the spring 213 a greater compression than its initial compression. The spring 213 is given an initial compression which presses the washer 215 (Fig. 6) against the sleeve 285 and the washer 211 against the end of the cylinder. The linkage 245 is said to be in compression when the rod 261 is thrust into the cylinder. beyond the position shown in Fig. 6, and is in tensionwhen a. force is applied tending to separate' the rod and cylinder.

As previously stated, the linkage 245 is in tension in theclosed'position of the breaker. The

tension ofthe linkage 245 in this circumstance biases the triplever 225, and by means of the links 23|, biases the armature 2|9 in a counterclockwise directionbr to unattracted position. Normal voltage on the circuit controlled by the breaker energizes the electromagnet 2|1 (Figs. 1 and 4) suiciently to hold the armature 2 I9 in its attracted position against the biasing inuence of the resilient linkage 245.

When the voltage drops below a predetermined value; for example, 50% of normal voltage, the attraction of the magnet for the armature 2|9 is reduced to a point where the spring 213 in the linkage 245 overcomes the magnetic pull and rocks the trip lever 225 and the armature 2H counterclockwise to the unattracted position of the armatures The counterclockwise movement of the trip lever 225 causes the screws 239 to rock the arm 243 and the trip bar |81 clockwise. This action, as previously described, thrusts the trip rod |35 upwardly and trips-the breaker causing the contacts to open as previously described. The .parts are shown in Fig. 4 at Athe instant the undervoltage trip device has tripped the breaker but before the contacts have opened.

The clockwise movement of the contact arm 30 to open the Contacts is transmitted bythe link 29| y(Fig. l) to the arm 283 and rocks this arm and the arm 241 also in a clockwise direction. The resilient linkage 245 transmits the clockwise movement ofthe arm 241 to the trip lever 225 restoring the trip lever in a clockwise direction to normal position and through the links 23| moves the armature 2|9 to its attracted position. f

During the latter portion of this movement, the rod 281 telescopes into the cylinder 26| placing the linkage 245 in compression thereby permitting overtravel of the arms 241 and 283 without subjecting the parts to undue strain. f

If the voltage on the line controlled by the breaker returns to normal before the contacts are closed manually by operation oi the handle |4|, or automatically through the agency of the motor |39, the undervoltage magnet 2|1 will be energized suiciently to hold the armature 2|.9 in attracted position. In this case, movement of the contact arm 30 to close the contacts causes the linkage 245 to again be placed under tension in readiness for `another undervoltage tripping operation.

Ii, however, the contacts should be closed against an undervoltage condition in the circuit, the magnet 2|1 will not have sufficient pull to hold this armature 2|9 and the trip lever 225 against the force exerted by the spring 213 in the linkage 245. This will result in moving the trip lever 225 to immediately trip the breaker open. It can, therefore, be seen that the breaker is trip free of the handle, that is, an undervoltage circuit condition will cause the breaker to trip open irrespective of the position of the handle.

It will also be apparent from the foregoing description that they provision of the -resilient linkage protects the parts from undue strain and breakage. This linkage not only provides the energy to trip the breaker upon the occurrence of a predetermined voltage drop but also transmits the force for automatically resetting the trip device upon opening movement of the contact arm 30.

The provision of the time delay device makes possible the correction of a momentary voltage drop without disrupting the circuit or service. The time delay may be omitted in which case the breaker will be tripped open instantaneously upon the occurrence of a predetermined Voltage drop.

Another important feature of the undervoltage device is the absence of latch mechanisms thus providing a simple reliable and inexpensive construction.

Certain features shown and described but not claimed in this application are fully disclosed and claimed in the aforementioned copending appli'- cation of John W. May and Ture Lindstrom, Serial No. 391,625, filed May 3, 1941, and assigned to the .assignee of this invention.

Having described a preferred embodiment of the invention in accordance with the patent statutes, it is to be understood that various changes and modications may be made therein without departing from some of the essential features of the invention. It is, therefore. desired the language oi the appended claims be given as reasonably broad interpretation as the prior art permits.

We claim as our invention:

1. In a circuit breaker, relatively movable contacts, operating mechanism for said contacts, trip mechanism including a resilient means connected to a part movable with the movable contact and operable to trip the circuit breaker operating mechanism, and a trip device operable in response to predetermined circuit conditions to initiate an operation of the trip mechanism, said resilient means being movable by the opening operation of the breaker to reset the trip device.

2. In a circuit breaker, relatively movable contacts, operating mechanism for said contacts, trip mechanism including a spring connected to a part movable with the movable contact and operable to trip the circuit breaker operating mechanism by energy stored in the spring by the closing movement oi the breaker, and an electromagnetic trip device including an armature normally restraining the spring but operable in response to predetermined circuit conditions to permit tripping operation of the spring, said spring being moved by the opening operation of the breaker to automatically reset the armature.

3. In a circuit breaker, relatively movable contacts, operating mechanism for said contacts, a trip mechanism including a resilient linkage operable to effect tripping of said circuit breaker operating mechanism, a trip device including an electromagnetic means for restraining the trip mechanism against operation, said electromagnetic means being responsive to predetermined circuit conditions to release the trip mechanism for a tripping operation, said linkage being moved by opening movement of the breaker to reset the trip mechanism and the trip device, and a time delay device comprising a dashpot having a retarding member operatively related to the tripping mechanism to delay tripping operation thereof and resettable independently of the resetting movement of the trip mechanism and the trip device.

4. In a circuit breaker, relatively movable contacts, operating mechanism for said contacts. a releasable trip mechanism including a spring operable to effect tripping of the circuit breaker operating mechanism, and an electromagnetic trip device for normally restraining said spring in operative condition, said trip device being operable in response to predetermined circuit conditions to release the trip mechanism for operation, said spring being operable by opening movement of the contacts to reset the trip mechanism and being restored to operative condition by closing of the contacts.

5. In a circuit breaker, relative movable contacts, operating mechanism for said contacts, a trip member operable to cause opening of the contacts, a resilient linkage biasing the trip member in tripping direction at least when the contacts are closed, and an electromagnetic trip device operable in response to predetermined circuit conditions to permit said resilient linkage to move the trip member to trip the breaker, said linkage being moved by the opening movement of the breaker to reset the electromagnetic trip device and the trip member.

6. In a circuit breaker, relatively movable contacts, operating mechanism for said contacts, a trip mechanism comprising a trip member operable to cause opening of the contacts and spring a,sse,oso

means biasing said trip member in tripping direction at least when the contacts are closed. and an electromagnetic trip device operable in response to a predetermined drop in voltage to permit said spring to operate said trip member. said spring means being operable by opening movement of the contacts to reset the trip member and the trip device.

7. In a circuit breaker, relatively movable contacts, a switch member movable to open and close said contacts, actuating mechanism for moving said switch member to open and to closed circuit positions, a trip mechanism including a spring biased to effect an opening operation of the switch member, and an electromagnet for holding the trip mechanism in operative position, said electromagnet being operable in response to predetermined circuit conditions to release the trip mechanism, and said spring being operable by the switch member when said switch member is moved to open position to restore the trip mechanism to operative position.

8. A circuit breaker comprising relatively movable contacts, operating mechanism for said contacts, means comprising a spring connected to a part movable with the movable contact. said spring being stressed when said contacts are closed and being operable to eect an operation of the operating mechanism to open the contacts, and electromagnetic means including an armature for holding said spring in stressed condition and operable in response to predetermined circuit conditions to permit operation of the spring, the movement of the movable contact to open position acting through said spring to reset the armature to holding position.

9. A circuit breaker comprising relatively movable contacts, a switch member operable to open the contacts, operating mechanism for said switch member, a trip member operable to cause opening of the contacts, a resilient linkage connecting the switch member to said trip member, said resilient linkage biasing the trip member in tripping direction at least when the contacts are closed and acting when released to operate the trip member, holding means comprising an electromagnet for releasably restraining the trip member, said electromagnet being responsive to predetermined voltage fluctuations in the circuit to release the trip member, and said resilient linkage acting to transmit the movement o! the switch member when said switch member operates to open the contacts to reset the trip member.

l0. In a circuit breaker, relatively movable contacts, operating mechanism for said contacts, a switch member movable to open and close the contacts, a trip member operable to cause opening of the contacts, a spring connected between a part that is moved during closing ot the breaker and said trip member, said spring biasing the trip member in tripping direction at least when the contacts are closed and acting when released to operate the trip member, an electromagnet having an armature operatively connected to the trip member for restraining the trip member against the action of said spring, said electromagnet being responsive to predetermined voltage conditions in the circuit to permit the spring to operate the trip member, said spring acting to transmit the movement of the switch member when said switch member moves to open the contacts to restore the trip member to operative position.

l1. In a circuit breaker, relatively movable contacts, operating means for said contacts, a trip 12. In a circuit breaker, relatively movable cony tacts, operating mechanism for said contacts, tripping mechanism .including a resilient linkage operable to effect opening of the contacts, an electromagnet having an armature operatively connected to the trip mechanism for holding said trip mechanism against the action of said resilient linkage, said electromagnet being responsive to predetermined circuit conditions to permit operation of the trip mechanism, a time delay device comprising a dashpot operatively connected to the armature for opposing tripping movement of said armature to delay the operation of the trip mechanism, said resilient linkage being operable by opening movement of the contacts to reset the armature to holding position, said armature being movable relative to said dashpot when the armature is moved to reset position, and spring means for resetting said dashpot.

13. In a circuit breaker, relatively movable con` tacts, operating mechanism for said contacts, tripping mechanism including a resilient means operable to eiect opening of the contacts, a trip device including an electromagnet having an armature operatively connected to the tripping mechanism for restraining said tripping mechanism in operative position, said electromagnet being operable in response to predetermined voltage conditions in the circuit to release the tripping mechanism for a` tripping operation, a time delay device for delaying tripping operation of the tripping mechanism but which permits quick resetting of said tripping mechanism, said resilient means being operable by opening movement of the contacts to restore the tripping mechanism to operative condition, and a separate spring for restoring said time delay device toy operative condition. f

i4. A circuit breaker comprising relatively movable contacts, operating mechanism for said contacts, means comprising a spring connected to a part movable with the movable contact, said spring being in a stressed condition when the contacts are closed and being operable to effect an operation of the operating mechanism to open the contacts, and electromagnetic means including an armature for restraining said spring in stressed condition and being operable in response to predetermined circuit conditions to permit operation of the spring, the movement of the contacts to open position acting through said spring to reset the armature to restraining position and the movement of said contacts to closed position acting to stress the spring;

15. A circuit breaker comprising relatively movable contacts, a switch member movable to an open position and to a closed position to open and close the contacts, operating mechanism for said switch member, a trip member operable to effect opening movement of the switch member, means comprising a spring connecting the switch member to said trip member, said spring having energy stored therein when the switch member is in closed position and being operable to effect an opening movement of the switch member, an electromagnetic means for restraining said spring and being operable in response to predetermined circuit conditions to permit the spring to operate said trip member, the movement of the switch member to open position acting through said spring to reset the trip member and the movement of the switch member to closed position acting to store energy in the spring.

16. A circuit breaker comprising relatively movable contacts, operating mechanism for said contacts, means comprising a spring connected to a part movable with the movable contact, said spring being stressed when the contacts are closed and being operable to effect an operation of the operating mechanism to open the contacts, and electromagnetic means for holding said spring in stressed condition and operable in response to predetermined circuit conditions to permit operation of the spring, the movement of vthe contacts to openfposition acting through said spring to reset the holding means to holding position, said spring being eective to permit overtravel of the parts connected thereto. l

GEORGE G. GRISSINGER. TURE LINDSTROM. 

